Breast cancer is the most common type of cancer in women. Its traditional diagnosis methods either have low sensitivity or high rate of false positive, making early diagnosis of breast cancer challenging. This project aims to detect breast cancer-specific, non-invasive, non-coding nucleic acid biomarkers from the plasma, cancer cells and tumor tissues of human breast cancer patients, for the purpose of discovering a new method of early breast cancer diagnosis. Our method first uses phage-based nanoparticles to capture the breast cancer-specific nucleic acid biomarkers (the target molecules) to form a complex, which carries the concentration information of both target biomarkers and phages. Then the phages are separated from the complex and titered to determine the concentration of phages, which in turn leads to the quantification of the target biomarkers. Specifically, we will first find out the best conditions for the multiplexed detection of breast cancer-specific nucleic acid biomarkers in commercial human plasma in order to understand the effect of the parameters of the detection media on the detection sensitivity. We will then apply the same method to detect multiple breast cancer-specific target biomarkers from human breast cancer cells and tissues. Towards this end, the target biomarkers will be isolated from breast cancer cells and in vitro breast tumor tissues to form the solutions of the target biomarkers by using a commercial kit. Then we will detect and quantify the target biomarkers from the resultant solutions. We will also detect the target nucleic acid biomarkers from total RNA solutions isolated from tumor tissues of breast cancer patients. This project will lead to phage-based method that can detect breast cancer-associated nucleic acid biomarkers from the plasma, cancer cells and tumor tissues of human breast cancer patients with high sensitivity, accuracy and reproducibility.